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Status of B s Mixing at CDF

Status of B s Mixing at CDF. Joseph Kroll (Penn) & Franco Bedeschi (INFN Pisa) Mixing Analysis Coordinators 15 October 2004 – CDF Collaboration Meeting. 2 nd St. Ocean City, NJ, 7 Feb 2004. Outline: Physics importance & current knowledge of  m s Method of measurement

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Status of B s Mixing at CDF

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  1. Status of Bs Mixing at CDF Joseph Kroll (Penn) & Franco Bedeschi (INFN Pisa) Mixing Analysis Coordinators 15 October 2004 – CDF Collaboration Meeting Kroll/Bedeschi Collaboration Meeting 2nd St. Ocean City, NJ, 7 Feb 2004

  2. Outline: • Physics importance & current knowledge of ms • Method of measurement • Organization of CDF B mixing analyses • Recent progress • Summary • Appendix: schedule Kroll/Bedeschi Collaboration Meeting Manasquan Inlet, NJ, 25 December 2003

  3. Goal of Flavor Physics Measure parameters of the CKM Matrix Test consistency: do measurements of the same parameter with different decays & CP asymmetries give the same result? Is it unitary? B0 flavor oscillations (md) measure one side How do B0s oscillations (ms) fit in this picture? Why is ms considered one of the most important Run II measurements? Kroll/Bedeschi Collaboration Meeting

  4. Neutral B Meson Flavor Oscillations Flavor oscillations occur through 2nd order weak interactions e.g. Same diagrams and formula for ms for Bs except replace “d” with “s” From measurement of md derive |V*tbVtd|2 All factors known well except “bag factor” £ “decay constant” md = 0.502 § 0.007 ps-1 (2%) (PDG 2004) from Lattice QCD calculations – see hep-ph/0406184 Kroll/Bedeschi Collaboration Meeting

  5. B Meson Flavor Oscillations (cont) md well measured: |V*tbVtd| limited by theoretical uncertainties If we measure ms then we would know the ratio ms/md Many theoretical quantities cancel in this ratio, we are left with from Lattice QCD – see hep-ph/0406184 This is why ms is high priority in Run II Since Vts ¼ Vcb this gives us our side Kroll/Bedeschi Collaboration Meeting

  6. Current Status of ms ms > 14.5 ps-1 95% CL Results from LEP, SLD, CDF I Amplitude method: H-G. Moser, A. Roussarie, NIM A384 p. 491 (1997) see http://www.slac.stanford.edu/xorg/hfag/osc/winter_2004/index.html Kroll/Bedeschi Collaboration Meeting

  7. Experimental Steps for Measuring Bs Mixing 1. Extract B0s signal – decay mode must identify b-flavor at decay (TTT) Examples: 2. Measure decay time (t) in B rest frame (L = distance travelled) (L00) 3. Determine b-flavor at production “flavor tagging” (TOF) “unmixed” means production and decay flavor are the same “mixed” means flavor at production opposite flavor at decay Flavor tag quantified by dilution D = 1 – 2w, w = mistag probability Kroll/Bedeschi Collaboration Meeting

  8. Measuring Bs Mixing (cont.) 4. Measure asymmetry Asymmetry is conceptual: actually perform likelihood fit to expected “unmixed” and “mixed” distributions Measure md to validate procedure these formulas assume perfect resolution for t Kroll/Bedeschi Collaboration Meeting

  9. Comment on : Time Integrated Mixing is the time integrated mixing probability In principle, a measurement of  determines m - the first Bd mixing measurements were  measurements - d = 0.186 § 0.004 (PDG 2004) - this does not work for Bs: s = 0.5 (the limit as x!1) A measurement of is very interesting Kroll/Bedeschi Collaboration Meeting

  10. B Flavor Tagging We quantify performance with efficiency and dilution D = fraction of signal with flavor tag D = 1-2w, w = probability that tag is incorrect (mistag) Statistical error A on asymmetry A (N is number of signal) statistical error scales with D2 Kroll/Bedeschi Collaboration Meeting

  11. Produce bb pairs: find 2nd b, determine flavor, infer flavor of 1st b Two Types of Flavor Tags Opposite side + Applicable to both B0 and B0s −other b not always in the acceptance Same side Based on fragmentation tracks or B** + better acceptance for frag. tracks than opp. side b −Results for B+ and B0not applicable to B0s Reminder: for limit on ms must know D Kroll/Bedeschi Collaboration Meeting

  12. Same Side Flavor Tags Based on correlation between charge of fragmentation particle and flavor of b in B meson Decay of P-wave mesons B** also contributes to B0, B+ (not B0s) Expected correlations different for B+, B0, B0s TOF Kroll/Bedeschi Collaboration Meeting

  13. Illustration of Bs Oscillations Example of Asymmetry with lots of statistics ms = 20 ps-1 Illustrated are - tagging reduces statistics dilution reduces amplitude - decay length resolution damps amplitude further - momentum uncertainty damps amplitude more as decay time t increases Large ms: Bs! Ds l  no good need fully reconstructed decays e.g., Bs! Ds Kroll/Bedeschi Collaboration Meeting

  14. CDF Bs Mixing History & Organization • Expected Bs mixing to come early in Run II • turned out not to be the case • Bs task force created by Tony Liss late Fall 2003 • Task force report issued June 2004 (CDFNOTE 7042) • MACs appointed to help organize & coordinate • Franco Bedeschi (INFN-Pisa) & Joseph Kroll (Penn) • MACs began in June 2004 • Have held three workshops • 9 June 2004 • 12 July 2004 (close out on 14 July) • 1 October 2004 • Current focus is Winter Conferences 2005 • Also planning for longer term: Summer 2005 & beyond Kroll/Bedeschi Collaboration Meeting

  15. Flavor tagging continued PID around B mesons (D. Usynin/Penn) SSKT MC studies (P. Catastini/Pisa) Status of PID (R. Snider/FNAL) Fitting for md Terms for likelihood(I. Kravchencko/MIT) md with J/ K (N. Leonardo/MIT) md with semileptonics (G.Giurgiu/CMU) Preparing for results on ms t in SST biased samples (discussion) Summary and Schedule (J. Kroll/Penn) see B meeting on 14 October Introduction (F. Bedeschi/Pisa) Proposal for blind analysis (G. Punzi/Pisa) Status of data sets (Ch. Paus/MIT) Signals Semileptonic (G. Gomez-Ceballos/MIT) Hadronic (A. Belloni/MIT) Ds+! K0S K+ (M. Casarsa/Padova) Status of lifetimes Semileptonic (S. Farrington/Liverpool) Hadronic (F. Azfar/Oxford) Flavor tagging Summary of OSTs (I. Kravchenko/MIT) Plan for SSKT (F. Bedeschi/Pisa) Monte Carlo Tuning (E. Ben-Haim/Paris6) Workshop Agenda from 1 October 2004 Big effort involving > 20 CDF institutions also involved: ANL, Brandeis, Cantabria, Chicago, Geneva, JHU, Karlsruhe, LBNL/Berkeley, Pittsburgh, Purdue, Rome, Tsukuba, Yale Kroll/Bedeschi Collaboration Meeting

  16. Significant Progress Since June 2004 • Blessed Mixing w SST & OST in l + D (CDFNOTE 7127) • Blessed update mixing w SST in hadronics (CDFNOTE 7145) • Blessed several flavor tags • improved soft muon tag (CDFNOTE 7043) • improved/extended jet charge tag (CDFNOTE 7131) • new soft electron tag (CDFNOTE 7121) • Blessed improved evaluation of sensitivity (CDFNOTE 7170) • Updated semileptonic/hadronic signals (PR plots) • All of above presented at ICHEP 2004 (50% B Summer 04 results) • improved lifetime resolution w event-by-event PV & L00 • Studies of SSKT underway – using TOF & dE/dx, MC tuning • Working towards competitive limit on ms for Winter 2005 • summary of activities with people & schedule appended at end of talk Kroll/Bedeschi Collaboration Meeting

  17. Examples of Progress on B0s Signals “Golden mode” Ds mode Kroll/Bedeschi Collaboration Meeting

  18. Examples of B0 & B+ Calibration Signals 6 & 8 track modes! Kroll/Bedeschi Collaboration Meeting

  19. Progress on Lifetimes Know how to measure lifetimes when there is no SVT trigger bias CDF: (B+)=1.662 § 0.033 § 0.008 ps (PDG 2004 (B+) = 1.671 § 0.018 ps) Do we get correct lifetime from SVT biased signals? Expect 488 m (14) Outstanding mystery in lepton + SVT sample Recent progress in understanding what is NOT the problem Need result from B! D (2 SVT) Kroll/Bedeschi Collaboration Meeting

  20. jet from b (b) has negative (positive) charge on average Results on Opposite Side Flavor Tags Lepton tags lower  higher D mistags from SLT(): D2 = (0.70 § 0.04 § 0.05)% SLT(e): D2=(0.37 § 0.03 § 0.06)% Jet charge tag Run II: D2 = (0.72 § 0.03)% higher , lower D includes lifetime info too Kaon tag Run II: no useful tag yet (have seen D,  too low) Largest D2 @ B factories TOF Kroll/Bedeschi Collaboration Meeting

  21. B pTrel  Fully Exploit Tag Power by “Binning” e.g., pTrel for soft leptons Larger pTrel increases b! suppresses b! c!, fakes pTrel Dilution dependence determined from data Requires enormous statistics of lepton + SVT sample Kroll/Bedeschi Collaboration Meeting

  22. Fully Exploit Tag Power by “Binning” e.g., Qjet for jet-charge Dilution increases with Q_{jet} Need unbinned likelihood fit to exploit dilution binning Kroll/Bedeschi Collaboration Meeting

  23. Progress on Same Side (Kaon) Tagging • SST (re)established in Run II in B0 mixing • B0: D2 = (1.04 § 0.15 § 0.17)% • B+: D2 = (4.69 § 0.49 § 0.36)% • SSKT predicted to be most powerful flavor tag for Bs • Problem: cannot measure D without seeing oscillations • Limit requires knowledge of D (to predict sensitivity) • do not know if Monte Carlo prediction of D is reliable • Have ambitious program to compare data and MC for SST • established short term goals • comparison of fragmentation particles in Monte Carlo to data • establish B** signals • measure kaons around B+, B0, Bs in data & MC – should see difference • Best performance of dE/dx and TOF is critical Kroll/Bedeschi Collaboration Meeting

  24. Fit for md & D in lepton + D with OSTs 1st time in Run I or II (only SST in Run I) • md = 0.593 § 0.53 ps D2 = 0.8% (OST only) D2 = 1.8% (OST & SST) soft muon tag D = (28§2)% These are binned asymmetry fits Do not exploit full power of OSTs (binning in Qjet, pTrel not used) SECVTX Jet Charge D = (19§ 1)% Kroll/Bedeschi Collaboration Meeting

  25. ICHEP 2004: Our Projected Sensitivity See CDFNOTE 7170 v2.0 Uses full unbinned likelihood to estimate sensitivity for l Ds (more like 74 fs) Baseline: D2 = 1.6% (OST only)  = 67 fs (achieved) (OST is SLT(e) = 0.4% + SLT() = 0.7% + JQT = 0.7%) Stretch: D2 = 2.6% (add SST)  = 47 fs (L00, event by evt. PV) Kroll/Bedeschi Collaboration Meeting

  26. ICHEP 2004 Projected Sensitivity (cont) Hadronic Semileptonic Kroll/Bedeschi Collaboration Meeting

  27. ICHEP 2004 Projected Sensitivity (cont) Message: even with only OST could have sensitivity comparable to best experiment. Good motivation to work hard Combined semileptonic and hadronic Kroll/Bedeschi Collaboration Meeting

  28. Highest Priority Items • Unbinned likelihood fit for md exploiting full power • of flavor tags, event by event t, S/B in different modes, etc. to accomplish 1. we must 2. Resolve lifetime problem in semileptonic modes (l Ds) 3. Measure lifetime in SVT-biased hadronic modes (Ds, etc.) With blessed OST’s, 1, 2, & 3 may be enough to say something 4. Study SSKT – determine defensible D from data and MC in parallel with 1, 2, 3 Kroll/Bedeschi Collaboration Meeting

  29. Summary • Large group of people (> 20 institutes) dedicated to crucial components of Bs mixing measurement • Significant progress was made this summer – we continue to work towards a 1st result in Winter 2005 • A lists of tasks with responsible people & deadlines is available – see Appendix to this talk. It will continue to evolve. There is still room to get involved This is a long term analysis It is a collaborative effort “No physicist left behind” Kroll/Bedeschi Collaboration Meeting

  30. Appendix: Schedule • Notes: • There is a web page in preparation – see B web page • The names on the following schedule indicate the people • who are responsible for the particular tasks now & in the • future. Many other collaborators contributed to these tasks • in a significant way in the past. Kroll/Bedeschi Collaboration Meeting

  31. Schedule • We have put together a list of tasks • Each task has • list of people doing the work • these people are considered “responsible” for delivering • the venue where they report the results of their work • specify the subgroup or B group • the various near term tasks including time estimates • long term tasks have more vague time estimates • Weekly status reports • we want status reports at subgroups on key tasks every week • does not have to be full presentation, can be one slide on previous week’s activities Kroll/Bedeschi Collaboration Meeting

  32. Data set definition 5.3.X all data up to August 2004 shutdown except COT compromised Good run list Furic & Nahn reports at BPAK by 4 November 2004 Skim of SVT two track data set Belforte, Casarsa, Delli, Fella, Lucchesi reports at BPAK 2 sections of the data up to 13 February 2004 after COT recovery Skim (continued) Status of data up to 13 Feb 2004 Bs! Ds, Ds! K*K or KSK complete finish other 7 modes by 4 Nov 2004 B-! D0-, D0! K+-, K+-+-, K+K-, +- B0! D-+, D-! K-++ B0s! Ds-+, Ds!,  post COT recovery data processing in parallel with above complete by end of November 2004 Some modes not included e.g., B! D* & D can be added – no time estimate Data Sets Kroll/Bedeschi Collaboration Meeting

  33. B Sntuple Paus reports at BPAK based on 5.3.1 includes all modes will include all data to Aug 2004 J/ K by 18 Oct 2004 lepton + D by 26 Oct 2004 B hadronic by 8 Nov 2004 Direct access to data (datlists) Furic & Paus reports at BPAK available 1 Dec 2004 Comments must do better for Summer 05 & beyond need to start organizing this now volunteer (BPAK) needed for Winter 2004 success of datlists is critical B sntuple no update of TOF possible event by event PV, L00 not included in present production 1 Oct 2004: Ch. Paus reports 30 pb-1 data bad due to CMX – use anyway? Data Sets (continued) Kroll/Bedeschi Collaboration Meeting

  34. Signal Optimization • Hadronic modes • Casarsa, Lucchesi, Squillacioti, Shapiro • reports at B Hadronic • complete by 4 Nov 2004 • Semileptonic modes • Gibson • reports at Semileptonics • update on 26 Oct 2004 • schedule for finalizing not established Concern: inadequate personnel and coming too late Kroll/Bedeschi Collaboration Meeting

  35. Semileptonic Clark, Farrington, Tanaka, Ukegawa, Uozumi reports at Semileptonics near term (by 4 Nov 2004) Tanaka x-check of l + D+ d0 cut on D* (D+, D0 too?) generate more c-cbar MC result in 8 GeV (no SVT) long term (no estimate) have to see results of near term to decide how to proceed Hadronic “MC free” approach Azfar, Boudreau, Huffman, Rademacher, Rahaman reports at B hadronic fitting test and refinement Azfar, Rademacher B+! D0+ in progress stripping & ntuple production (data & MC) Azfar, Rahaman B+! D0+ done B0, Bs, &b modes in progress complete by 4 Nov 2004 Lifetimes Kroll/Bedeschi Collaboration Meeting

  36. Hadronic “MC free” continued Systematics alignment (Boudreau, Rahaman) SVT eff. (Azfar, Rademacher) background parameterization (Huffman, Rademacher) all in progress already for B+ mode – done by 4 Nov 2004 others follow later Hadronic – SVT eff. method Da Ronco, Donega, Giagu, Giolo, Lucchesi update SVT  curves by 4 Nov 2004 preliminary result (lifetime okay or not okay) by 22 Nov 2004 Lifetimes (continued) Kroll/Bedeschi Collaboration Meeting

  37. Opposite Side Flavor Tags • Validation of blessed Summer 2004 SLT(), SLT(e), JQT • Giurgiu, Kravchenko • reports at Semileptonics • means putting taggers in repository & verifying we get the same results • complete by 19 Oct 2004 • Creation of simple combination of above tags • Giurgiu, Kravchenko • reports at Semileptonics • determine tag overlaps and combined  D2 (including binning) on J/K • report on 19 Oct 2004 • evaluation of more sophisticated combinations (max D, diff. classes) • time scale not established Kroll/Bedeschi Collaboration Meeting

  38. Same Side (Kaon) Tag • Further development of SS(K)T • Bedeschi, Catastini, Punzi, Scuri, Squillacioti • reports to Semileptonics • compare SS(K)T algorithms in data & MC using J/ K samples • use combined dE/dx & TOF particle ID • report by 4 Nov 2004 • Study particle species produced around B+, B0, B0s • Heijboer, Jones, Kroll, Usynin • reports to Semileptonics • Measure particle species in data • initial report using private TOF calibration in July 2004 • further progress requires updated TOF calibration and B Sntuples • MC production in parallel – estimate Dec 2004 Kroll/Bedeschi Collaboration Meeting

  39. Same Side Kaon Tag (continued) • Comparison MC & data, tuning fragmentation • Ben-Haim, Maksimovic, Pursley • reports to Monte Carlo & Semileptonics • update on 4 Nov 2004 • B** • Ben-Haim, Maksimovic, Pursley • reports to J/ & B hadronics • signal in B+! J/ K+ (update 4 Nov 2004) • signal in SVT hadronic samples (December?) Kroll/Bedeschi Collaboration Meeting

  40. MIT/Cantabria/Karlsruhe Belloni, Gomez-Ceballos, Kravchenko, Leonardo, Paus, Piedra reports to Semileptonics likelihood fit B!J/ K with SST exists – see last workshop need to add OSTs developing fits for l + D & D, D3p Fully tested with preliminary result on md by 1 Dec 2004 Argonne/CMU Giurgiu, Paulini, Tanaka reports to Semileptonics full likelihood for ms exists; used for ICHEP 04 projections developing for md w l + D incorporating blessed OSTs 1st version fit working and tested on toy MC – see last workshop working on including tagging & vertexing in data ntuple – report at 4 Nov 2004 run on MC to determine add. K factors: 30 Nov 2004 1st result on md by 7 Dec 2004 Likelihood Fitting for md Kroll/Bedeschi Collaboration Meeting

  41. Result on ms • Difficult to work this far ahead – we can work backwards from La Thuile & draw some conclusions: • 24 Feb 2005 last day to bless results for La Thuile • 17 Feb 2005 unblind results on ms • 03 Feb 2005 prebless results on ms • 20 Jan 2005 bless results on md for ms (Collaboration mtg.) • 06 Jan 2005 prebless results on md for ms • Better have full likelihood machinery for md determination using hadronic and semileptonic samples and OSTs before the Winter holiday – this includes a substantial amount of documentation prepared. Kroll/Bedeschi Collaboration Meeting

  42. In Preparation for ms • Decision on blinding procedure • Punzi • reports to B meeting • written proposal submitted to B group before 4 Nov 2004 • present at workshop on 4 Nov 2004, sign off at following B meeting • Quantities for input to likelihood fit (flat file content) • Kravchenko & Tanaka • reports to semileptonics • written proposal submitted to B group before 4 Nov 2004 • present at workshop on 4 Nov 2004 Kroll/Bedeschi Collaboration Meeting

  43. Common Tools • dE/dx in COT • COT dE/dx group (Giagu) • reports to BPAK group • validation of entire data set up to Aug 2004 shutdown in progress • ready for 5.3.4 release on 29 Oct 2004 • TOF • TOF group (Snider) • reports to BPAK group • in process of revising/validating calibration schemes • hope to be ready for 5.3.4 release on 29 Oct 2004 Kroll/Bedeschi Collaboration Meeting

  44. Combined dE/dx & TOF PID Ciocci, Morello, Punzi, Squillacioti, Tonelli reports to BPAK available now in private version: resolution functions for each particle type separately for dE/dx & TOF include in public code infrastructure by 18 Oct 2004 – validate include in 5.3.4 release on 29 Oct 2004 include combination of TOF and dE/dx for 29 Oct 2004 release demonstrate utility with examples by 4 Nov 2004 Event by Event Vertexing incl. L00 Cerri, Lucchesi, Shapiro reports to BPAK code available & will be in 5.3.4 rel. documentation by 4 Nov 2004 Common Tools (continued) Kroll/Bedeschi Collaboration Meeting

  45. Monte Carlo Production • Oversight of Monte Carlo Generation/Production • D’Auria • reports to Monte Carlo • outstanding issues • existing MC samples produced by various groups privately not registered • only aware of one collaborative effort to generate MC for semileptonics • see talk by Usynin at semileptonics subgroup on 28 Sep 2004 Kroll/Bedeschi Collaboration Meeting

  46. Some Concluding Remarks • We have made progress assigning tasks and making a schedule • The schedule needs to be studied further to see if we are on target to have a result for Winter 2005 • Particular concern is Dec 2004 – how do we go from 1st results on md to documented blessed results by early Jan 2005? • Two more workshops planned in 2004 • November 3 & 4 • off week – we thought it would help to spread the pain over 2 days • December 16 Kroll/Bedeschi Collaboration Meeting

  47. Calendar Gasp! now we are here! on week proposed B mixing workshop Collaboration meeting last Thursday meeting holiday Better get back to work La Thuile begins here Kroll/Bedeschi Collaboration Meeting

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